Retro-reflectivity is the property where incident light from a localized source, for example a headlight, flashlight, or the moon, is mostly returned to the source even if the reflecting surface is not facing the source. In addition, such surfaces scatter little light in other directions. Retro-reflective surfaces increase visibility in low visibility conditions. Clothes, decalcomanias, and signs are major end products for retro-reflective surfaces. Typically, such surfaces are constructed from an array of miniaturized refractive elements bonded onto a reflective surface. Common retro-reflectors include metal-coated high index glass spheres and cube corner prisms with metalized back coatings. The retro-reflective surfaces themselves are sown or otherwise bonded onto an article that is desired to have an area of retro-reflectivity. Fibers with innate retro-reflectivity have remained elusive to date. Prior attempts to produce, via extrusion, such a fiber have included uniform circular cross-section fibers and star-shaped cross-section fibers, the latter being designed to mimic a cube corner retro-reflector with 90° inner angles and a reflective coating.
Although known retro-reflectors and techniques for using them have proven useful, there are disadvantages and drawbacks. Room for improvement remains and would be a welcome advance in the art.